The iPhone Dev-Team has announced RedSn0w 0.9.15b1 which brings numerous new features including iOS 6 jailbreak for old devices, ability to restore to older firmware, manipulating SHSH blobs and etc.

iOS 6 jailbrak is tethered for iPhone 4, iPhone 3GS and iPod Touch 4G, untethered only for old iPhone 3GS with old bootrom. Tethered jailbreak means that each time you restart your device you will need to connect it to a computer and run redsn0w.